My dropdown menu from the navbar is triggered by a toggle button. To indicate that it points to the trigger button, I added a triangle above the navbar-collapse. While this works well on larger screens, on mobile devices, it keeps getting pushed behind the navbar. I've tried adjusting the z-index without success.
http://www.bootply.com/g8d0nLzlIE
To improve visibility on mobile, I changed the color of the triangle to grey instead of white as used on the desktop version for better contrast.